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Prototype Friden 130 Etched Circuit Board

This is a very early prototype board for the Friden 130 that tested the flow-solder process on a populated circuit board to make sure that there were no problems with solder bridges. If one carefully inspects the circuit board, a number of small arrow-shaped "flags" made of masking tape are placed on the board to indicate the occurrence of solder bridges that formed between component leads and adjacent circuit board traces. Finding these problems led either to minor circuit board trace routing changes that eliminated the chance for solder bridges to form, or changes in the shaping of the component leads to minimize the chance of bridging.

Note also the inconsistent mounting of transistors toward the left end of the board. Stuffing a test board with actual components can expose spacing issues which can require subtle changes to the circuit board layout and drill patterns. In this case, some changes were made to the production circuit board for allow for more consistent component placement.

The circuit board is the "G" board of the Friden 130, which contains circuitry relating to generation of the analog signals that operate the CRT display.

Sincere thanks to Dick Ahrens, former Friden employee, for donation of this wonderful artifact to the Old Calculator Web Museum.

Text and images Copyright ©1997-2011, Rick Bensene.